public interface DiscountStrategy {    public double getTotal(double price);}public class VIPDiscount implements DiscountStrategy {    //95折    @Override    public double getTotal(double price) {        return 0.95*price;    }}public class ActivityDiscount implements DiscountStrategy{    //9折    @Override    public double getTotal(double price) {        return 0.9*price;    }}public class StoreDiscount implements DiscountStrategy{    //满500超出部分打6折    @Override    public double getTotal(double price) {        return 500+0.6*(price-500);    }}

public abstract class CompositeDiscount implements DiscountStrategy {    protected List<DiscountStrategy> strategies =new ArrayList(); //容器    public void add(DiscountStrategy discountStrategy){ //添加叶子结点        strategies.add(discountStrategy);    }    @Override    public double getTotal(double price) {        return price;    }}//多种折扣选最低折扣public class SingleMinStrategy extends CompositeDiscount {    @Override    public double getTotal(double price) {        double rtn=price;        for (DiscountStrategy s: strategies) {            rtn=Math.min(rtn,s.getTotal(price));        }        return rtn;    }}//多种折扣用折上折public class MultipleStrategy extends CompositeDiscount {    @Override    public double getTotal(double price) {        double rtn = price;        for (DiscountStrategy s : strategies) {            rtn = s.getTotal(rtn);        }        return rtn;    }}

public class DiscountFactory {    public DiscountStrategy create(String type){ //工厂来创建相应策略        //单一折扣策略        if("ynn".equals(type))return new VIPDiscount();        else if("nyn".equals(type))return new StoreDiscount();        else if("nny".equals(type))return new ActivityDiscount();        else{  //多种折扣策略            CompositeDiscount compositeDiscount;            System.out.println("请选择冲突解决方案：1.折上折 2.最低折");            Scanner scanner=new Scanner(System.in);            int type2=scanner.nextInt();            if(type2==1){                compositeDiscount=new MultipleStrategy();            }            else{                compositeDiscount=new SingleMinStrategy();            }            if(type.charAt(1)=="y")compositeDiscount.add(new StoreDiscount());            if(type.charAt(0)=="y")compositeDiscount.add(new VIPDiscount());            if(type.charAt(2)=="y")compositeDiscount.add(new ActivityDiscount());            return compositeDiscount;        }    }}

public class Order {    public double price;    private String type;    public DiscountStrategy discountStrategy;    public Order(double price) {        this.price=price;    }    public void display(){        System.out.println("总价："+price);        System.out.println("是否是VIP？y/n");        Scanner scanner=new Scanner(System.in);        type=scanner.next();        System.out.println("是否超过500？y/n");        String tmp;        tmp=scanner.next();        type+=tmp;        System.out.println("是否满足活动价？y/n");        tmp=scanner.next();        type+=tmp;        DiscountFactory discountFactory=new DiscountFactory();        double discountPrice=discountFactory.create(type).getTotal(price);        System.out.println("优惠："+(price-discountPrice));        System.out.println("应付："+discountPrice);    }}public class Client {    public static void main(String[] args) {        Order order=new Order(620);        order.display();    }}